In the field of biochemical reactions such as DNA reactions and protein reactions, techniques called μ-TAS (Total Analysis System) and Lab-on-Chip have been conventionally known in a reactor for treating a trace amount of sample solution. In these techniques, a plurality of reaction chambers (hereafter, referred to as wells) and flow passages are provided in a single chip or a cartridge. Thus, analysis of a plurality of specimens and a plurality of reactions can be carried out. These techniques have various advantages since the amount of chemicals to be handled can be reduced through miniaturization of the chip or the cartridge.
Examples of such advantages include: a reduction in the amount of conventionally used chemicals, such as strong acid and strong alkali, thereby dramatically reducing the impact on the human body and on the environment; and also a reduction in the consumption of expensive reagents used in the biochemical reaction or the like, thereby reducing the cost required for the analysis and reaction.
In order to carry out a biochemical reaction most efficiently using a chip or a cartridge, it is necessary that different types of chemicals, samples and enzymes are each disposed in a plurality of wells, and then, reagents for causing the reaction with these chemicals, samples and enzymes are collectively introduced into the wells through a single or a plurality of main conduits, thereby allowing a plurality of different reactions to proceed.
By using this technique, multiple types of specimens can be treated with the same reagent at the same time, or one type of specimen can be subjected to a plurality of treatments at the same time. As a result, it becomes possible to considerably reduce the time and labor required in the prior art.
When employing this kind of technique, a technique for supplying an equal amount of samples to a plurality of reaction fields and also a technique for preventing mixing of the contents in each well become important. Examples of the prior arts regarding such chips for supplying liquid samples to the wells include the following.
In Patent Document 1, in a chip that supplies liquid samples from a liquid reservoir to the wells by centrifugal force, flow channels are deformed and sealed so as to separate the wells. For this reason, a mechanism to crush the flow channels is required, making the automation difficult. In addition, if the liquid samples are supplied from the central liquid reservoir to the surrounding wells by centrifugal force as in the conventional centrifugally supplying chips, the amount of liquid samples supplied to each well varies.
In Patent Document 2, the problem of variations in the amount of liquid samples supplied to each well is solved by employing a centrifugal method that combines rotation and revolution. However, this technique also requires a complicated mechanism and space for rotating/revolving chips.
In Patent Document 3, a medium for analysis in which a liquid reservoir section and a plurality of wells having a flow channel extended in the centrifugal direction are connected has been disclosed. However, this document pays no attention to the delivery of liquids, but describes a fluid control through the pressing of air filled in the wells. In this technique, the result differs from reaction to reaction because not only the liquid in the channel between the two liquid reservoir sections is not supplied but also the amount of liquid supplied to each well varies greatly.
Therefore, the first problem associated with the prior art is the unavailability of chips employing a simple liquid supply method while reducing variations in the amount of liquid in each well.
In addition, as the second problem associated with these techniques, since it is necessary to deliver the sample material to a plurality of wells within an instrument, cross contamination may occur among the chambers, which leads to wrong test results.
As a technique for solving the above-mentioned problems, a sealed-type chip has been proposed, which is formed by pasting two members together, while at least one of the members has been processed and provided with a flow passage or the like. For example, in Patent Document 1, a sealed-type process array and a sample processing apparatus have been disclosed, that are constituted of a first principal surface member providing a structure that includes a loading chamber, a main conduit and a process chamber (well), and a second principal surface member, in which the process chamber is arranged alongside the conduit that extends from the loading chamber, and the loading chamber, the conduit and the process chamber are aligned alongside the longitudinal direction of the sample processing apparatus.
The process array described in Patent Document 4 is provided with a plurality of process chambers connected via feed conduits that are branched from one main conduit. For this reason, operations such as those to treat a plurality types of specimens with the same reagent are possible. In order to carry out biochemical reactions in the most efficient manner by using these process arrays, different kinds of chemicals, specimens and enzymes are first disposed in a plurality of reaction fields. Then the reagent that reacts with them is poured into the respective reaction fields from a single or a plurality of main conduits. It is necessary to cause several different reactions as described above. By employing this technique, multiple types of specimens can be treated with the same reagent at the same time, or one type of specimen can be subjected to a plurality of treatments at the same time. As a result, it becomes possible to considerably reduce the time and labor required in the prior art.
As this type of technique, for example, by employing a microfluid chip equipped with a liquid inlet, a flow passage, a liquid outlet and the like, a technique has been disclosed, in which a portion of reagent components required for the reaction is fixed within the chip flow passage in a solid state through a process such as freeze drying, the remaining portion of reagent components required for the reaction is supplied in a liquid state, and the reaction is allowed to proceed by bringing these components into contact within the flow passage.
In addition, Patent Document 5 discloses a sample processing apparatus formed by pasting together a resin substrate having a loading chamber, a process chamber and a flow passage formed therein, and a flat metal substrate. Further, when allowing different reactions to proceed in each process chamber, a method for blocking the flow passage so that each process chamber becomes an enclosed space has been disclosed. In this sample processing apparatus, the flat metal substrate is deformed so as to be forced into the flow passage, thereby blocking the flow passage.
However, a pressure sensitive adhesive is used between the first principal surface member and the second principal surface member in the process array described in Patent Document 1. The use of a pressure sensitive adhesive causes elution from the adhesive during reaction, which may adversely affect the reagent inside the well. In addition, problems of heat resistance or water resistance associated with the adhesive layer readily occurs, and the constitution described in Patent Document 1 is inadequate for sealing the flow passage in order to avoid the effects from the outside.
Moreover, it is extremely important to precisely control the reaction temperature or temperature cycling conditions when conducting biochemical reactions or the like. The metal substrate side is made into a flat plate shape in the sample processing apparatus described in Patent Document 2. It has been described that, for this reason, adhesion with the heating blocks or the like improves, which makes it suitable for the reactions involving thermal cycles. However, it is necessary to block the flow passage to form each process chamber into an enclosed space when carrying out reactions using the sample processing apparatus described in Patent Document 2. In this sample processing apparatus, the flat metal substrate is deformed so as to be forced into the flow passage, thereby blocking the flow passage. Due to deformation of the metal substrate as described above, the flatness of the metal substrate is impaired, the adhesion with the heating blocks reduces, and the thermal responsiveness becomes inadequate, which makes it difficult to carry out desired reactions reliably and within a short space of time. Moreover, in the method described in Patent Document 2, when the blocking of the flow passage is inadequate, cross contamination may occur among the chambers which leads to wrong test results.
[Citation List]
[Patent Documents]
[Patent Document 1] Published Japanese Translation No. 2004-502164 of the PCT International Publication
[Patent Document 2] Japanese Patent Publication No. 3699721
[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2008-83017
[Patent Document 4] Japanese Patent Publication No. 4181046
[Patent Document 5] Published Japanese Translation No. 2004-502164 of the PCT International Publication